1. Field of the Invention
There is a continuing need for rapid, accurate, qualitative and quantitative determinations of biologically active substances, e.g., antigens, antibodies, etc., at extremely low concentrations. There is a wide need for determining the presence of drugs in body fluids. In medical diagnoses, it is frequently important to know the presence of various substances which are synthesized naturally by the body or ingested.
Rheumatoid factor represents a heterogeneous population of auto-antibodies that bind to the Fc portion of IgG. It is primarily found as a pentameric IgG but both IgG and IgA forms of the molecule also exist. The detection of rheumatoid factor in serum is used in conjunction with other clinical symptoms for the diagnosis and treatment of rheumatoid arthritis.
The majority of commercial rheumatoid factor (RF) tests are subjective agglutination tests which depend on visual evaluation to determine a semi-quantitative RF titer. These agglutination methods, although simple, are non-instrumented, very subjective and require manual recording of test results. A convenient quantitative, and objective test for RF that can be readily instrumented to avoid transcription errors and permit automation would be useful to the clinician prescribing treatment.
2. Description of the Prior Art
Immunological studies using antigen-coated charcoal and their application to rheumatoid factor are discussed by Gottlieb, et al., Arthritis and Rheumatism, 10:199-203 (1967).
Optimization of a sandwich sol particle immunoassay for human chorionic gonadotropin is discussed by Leuvering et al. in the Journal of Immunological Methods (1983) 62:175-184. A homogeneous sol particle immunoassay for human chorionic gonadotropin using monoclonal antibodies is discussed by Leuvering et al. in the Journal of Immunological Methods (1983) 60:9-23. A homogeneous sol particle immunoassay for total oestrogens in urine and serum samples is disclosed by Leuvering et al. in the Journal of Immunological Methods (1983) 62:163-174.
U.S. Pat. Nos. 4,208,185 and 4,118,192 disclose method and apparatus for the measurement of antigens and antibodies. The detection of rheumatoid factor by antibody sensitized microbial particles is described in U.S. Pat. No. 4,189,466.
An agglutination assay for antibodies or antigens by complexion with first reagent particles and agglutinating with second reagent particles in described in Great Britain patent application No. GB 006,686 filed Feb. 26, 1979.
The immunological determination of immune complexes by reacting with immobilized antigen or antibody specific reagents and optionally labeled antibody or antigen specific reagents is disclosed in West German patent application No. DT-836046, filed Aug. 17, 1978.